Foot pump



Patented Sept. 8, 11953 FOOT PUMP Thure Hjalmar Bjurstrm, Hallstahammar,Sweden Application June 7, 1950, Serial No. 166,637 In Sweden June 21,1948 7 Claims. (Cl. 23o-172) The present invention relates to animproved y foot pump, particularly suitable for pumping air into thetyres of vehicles.

In known pumps of this kind the driving force applied to a pedal istransmitted by means of a lever or link arm system to a spring-loadedpiston adapted to reciprocate within a cylinder. This constitutes arather complicated mechanical construction which occupies a considerableamount of space and is relatively expensive in manufacture, and forthese reasons such known devices have not come into more extensive useas, for example a bicycle pump, in spite of the advantages they have ofbeing considerably less fatiguing to use than the common handpump.

According to the invention the aforesaid drawbacks may be avoided or, inany case, considerably reduced by disposing between the pedal and thepiston or pistons as a movement transmitting means a series of balls orrollers which are guided along a determined curved path of movement. Thepump according to the invention thus comprises only three moving means,viz. the piston and its associated piston rod, the series of balls orrollers, and the pedal. In pressing the pedal downwards the drivingforce for the exhaust or pressure stroke is transmitted to the pistonthrough the series of balls or rollers and upon releasing the pressureon the pedal the piston performs its suction stroke under the influenceof a spring stressed during the pressure stroke and the movement of thepiston is transmitted through the series of balls or rollers to thepedal, which is thus raised in readiness for the next pressure stroke.

In order further to simplify the manufacture and thus reduce theproduction costs the movable parts are conveniently mounted in a housingof moulded plastics, e. g. synthetic resinous material. In this mannerthe pump according to the invention may be made of particularly lowweight. Furthermore, the housing is preferably formed to enable the pumpto be directly connected to the air valve of, for example, a bicycletyre without using a rubber connector hose.

The invention will now be explained in greater detail in the followingdescription of one embodiment which is also shown in the accompanyingdrawings.

In the drawings:

Fig. 1 shows a longitudinal section and Fig. 2 an end view of a pumpaccording to the invention with the movable parts in the mutualpositions which they occupy at the beginning of a pressure stroke.

Fig. 3 is a longitudinal section showing the mutual positions of themovable parts at the end of the pressure stroke or the start of thesuction stroke.

Fig. 4 shows a top plan view of the embodiment while,

Figs. 5 and 6 are cross sectional views taken respectively on lines A-Aand B-B of Fig. 3 and seen in the direction of the arrows.

The pump housing comprises a front part I and a,rear part I I, thelatter being divided into two halves. Conveniently these parts are madeof moulded plastic material. The two halves of the rear part are heldtogether by screws I3 and are attached tothe front part by screws I2.

The front part I contains the pump cylinder I6 wherein a pistonconsisting of a packing 2, suitably made of leather, and washers 3 and 4operate. A piston rod 6 is attached to the piston by means of a screw 5.This piston rod first extends rearwardly from the piston for a distancesubstantially equal to the length of the pump cylinder and is then bentsubstantially through to form a knee 6 and a portion I'I extendingforwardly in a direction parallel with the axis of the cylinder I6. Theportion I'I is slidably mounted in a cylindrical chamber I8 disposed inthe front part I below and parallel with the cylinder IIr and thus formsa guiding means for the piston. Between the bottom of an axial boring I9in the portion I1 and the closed inner end of the chamber I8 there isdisposed a compression spring 'I tending to maintain the piston in itsrearward position as shown in Fig. 1.

In the adjacent faces of the halves of the rear part II are providedrecesses constituting a passageway I 9' permitting the piston rod tomove freely and grooves forming a channel 20 Ywhich rst forms a straightcontinuation of the chamberl and then bends upwards and opens at the topof the housing. A pedal 9 is pivoted on a pin I0 at the top of the frontpart I. The pedal extends rearwardly from the pin Ill over practicallythe whole length of the pump and carries on the lower side of its rearportion a slightly curved plunger ZI adapted to move in the upwardlyextending portion of the channel 20. Between the plunger ZI and the knee6 on the piston rod 6 lies a series of balls or rollers 8 which areguided in the channel 20. When, with the parts in the position shown inFig. 1, a downwardly directed pressure is applied to the rear portionsof the pedal 9, this pressure will be transmitted to the piston rod Ethrough the intermediary of the plunger 2l and the balls or rollers 8and under its influence the piston 2, 3, 4 will be forced forwardlywithin the cylinder I6 to perform a pressure stroke while at the sametime compressing the spring 1 in the chamber I 8. When the pressureapplied is removed the spring 1 drives the piston 2, 3, 4 backwards in,a suction stroke .fand :simultaneously the balls or rollers 8 arepushed `back so that the pedal 9 is raised again to its startingposition.

The forward end of the front part is formed into a slender and bentsnout or trunk 22 through which extends an exhaust channel l23 leadingfrom the pump cylinder I6 to a nipple I4 having a downwardly directedopeningV :containing a packing of rubber or the like so that ya tightconnection is obtained when the nipple isplaced on the valve of the tyrewhich is to be innated.

At its rearward loweredge the rear part II is provided withabroadgroovedinclined supportfing plate 24 softhat the pump will-reststeadilyon Vthe ground when thepedalis forced zdown.

tially aplane parallelwiththeground so that the 'operator may easilydepress the lsame and operate the pump.

'The invention must not be considered limited only Yto 'the embodimentdescribed in detail in vthe foregoing specification y.but comprises, ofcourse, also all such modifications and `changes thereof that -fallwithin thescopeaof .the following claims.

- vfclaim:

A1.-.A foot lpump comprising a housing provided ,at Vthe forward`endwith a cylinder having an air .discharge .outlet-and .with :achamber therebe- ,neath and parallelthereto, a spring in -the charnber,a `piston head in the --cylindeig a .piston rod .extending from -thehead `and having the 'outer f 'portion bent upon itself and arranged`-in `.sliding engagement .with the chamber against 4the ten- .sionofthe spring, a foot leverpivotally-connected to the top of `the .frontpartof lthe housing :and

extending above the housing, a=plunger;depend- 1';

,4 gaging extension is in operative position the nipple will be engagedwith a valve of a tire and the foot lever will be positioned insubstantially horizontal position with respect to the ground so that itmay be readily operated by foot pressure of the operator. Y

3A'ffoot pump as claimedin claim 1, wherein the4'anti-friction"meansincludesfa series of balls guided in the rearportion of the channel and in iinter-engagement with each other With theend .balls respectively contacting the bent portion of the piston rod onthe lower end of the plunger.

:14. :Afootspumpof the character described comprising a housing, thefront portion of which is provided with-a vcylinder having an airdischarge `outlet and with a chamber therebeneath and parallel thereto,while the rear portion is provided witha channel communicating with theouter end of the chamber, a piston head operating in the cylinder, apiston-rod extending `rearwardly lfrom Ltherheadrand having a portionbentdownwardly and forwardly for sliding Yengagenrient in the chamber,afoot .leverrhaving the innerend pivot- Yally mounted at Vthe -upperforward portion of the housing and overlying the same, a plungerdepending from the outer end of the lever and operable in thechannel, aflexible anti-friction connection operatively arranged in the channelbetween the bent portion ofthe piston rod and the plunger whereby whenpressure is placed on .the outer `end of the foot lever the .piston headAWillbe moved forwardly in the cylinder for the discharge of airtherefrom and the outer end of the piston rod. .will be moved into thechamber, andspringmeans in the chamber for turning the foot lever tonormal position.

5. .Afoot pump according .to claim 4, wherein ,the vflexibleanti-.friction means consists of a pluralityof .interengaging rollingelements directly contacting .the `bent portion `of the piston rod andthe plunger vand housed in and guided by the channel.

.6. A foot pump as vclaimed in claim 4, wherein ,the lhousing includesva rear part composed of two interconnected recessed sections which whenplaced together form the channel, and means for detachably connectingsaid sections to the front partof the housing.

7. A foot pump as claimed in claim 4, wherein the rear portion of the'housing has a foot portion extending therefrom at van upwardinclination and provided with a roughened surface, a nipple at theoutlet arranged at an inclination and'having the outer surface in aplane parallel with the foot extension and the foot lever being Valsonormally arranged at an inclination `and in a plane parallel with theouter surface of the nipple and the roughened foot portion.

THURE HJALMAR BJURSTRM.

References Vcited( in the me lof this patent UNITED STATES PATENTSNumber Name I Date 368,616 Schrankel Aug. 9, 1887 1,280,511 Macbeth Oct.1, 1918 2,338,869 Porter Jan. 11, 1944

